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For centuries, writers have waxed poetic about the damage sadness and despair
can cause to the heart. Today, scientists have proven them correct in a way.
Studies performed over the past decade have shown a definite link between
depression and heart disease.
Several studies confirm that heart attack patients with depression are much
more likely to die in the first six months after the event than heart attack
patients who are not depressed, according to Leo Pozuelo, M.D., Cleveland Clinic
staff psychiatrist. "With the wealth of information now available, we know
for a fact that not only is depression an independent risk factor for heart
disease, it’s just as significant as having high cholesterol or being a
smoker," he says.
Essentially, there are two ways that depression can become a risk factor in
the development or reoccurrence of heart disease. First, depression frequently
occurs in individuals after a major cardiac event such as a heart attack or
heart surgery, according to David L. Bronson, M.D., Cleveland Clinic internal
medicine specialist and co-author of the article, "Heart disease and
depression: Don’t ignore the relationship," published in the September
2003 issue of The Cleveland Clinic Journal of Medicine.
"If people get depressed after a heart attack, they are more likely to
have another heart attack or experience cardiac death in the next year,"
says Dr. Bronson. "So we believe it’s important to treat depression at
that point."
Second, depression increases the risk of heart attack in people who have no
history of cardiovascular disease. For instance, healthy individuals identified
with depression are twice as likely to develop cardiac disease over the next
decade as healthy individuals who experienced no depression over the same
period, says Cleveland Clinic psychiatrist Kathleen N. Franco, M.D., also a
co-author on the depression and heart disease article.
Chemical connection is culprit
The connection between depression and heart disease is primarily a chemical
one, says Dr. Bronson, mainly involving the hormones cortisol and serotonin.
Individuals who are depressed produce higher levels of cortisol, a
corticosteroid hormone that has many functions in the body. An otherwise
beneficial hormone, at abnormal levels cortisol can cause blood and blood vessel
problems—for instance clotting and inflammation—that are associated with
conditions such as hypertension and hypercholesterolemia (abnormally high
cholesterol).
Increased production of serotonin in people with depression increases
platelet activation, an early phase of the blood clotting process that can lead
to obstruction of the arteries through plaque formation, a hallmark of heart
disease.
People with depression also typically have decreased heart rate variability
(the beat-to-beat alterations in heart rate), which is even more significant in
patients with cardiovascular disease, says Dr. Pozuelo. "Some of the
studies done at the Clinic and elsewhere," he says, "indicate that if
you have decreased heart rate variability after a heart attack, you’re at a
higher risk of dying."
Treating depression to help the heart
All of these links are still being investigated; some current studies are
examining whether treating depression in patients with heart disease can help
improve their longevity. Patients with a first-time depression do not always
show improved cardiac health in the wake of treatment with antidepressants.
"We don’t know right now that treatment for depression increases your
life span after a heart attack," says Dr. Franco. "But there are
certain patients—for example, those who have had more than one bout of
depression—who are helped significantly by treatment for depression after a
heart attack," she says.
Studies have also shown that a class of antidepressant drugs known as
selective serotonin reuptake inhibitors (SSRIs) is especially effective for
patients with heart disease. In addition to improving depressive symptoms and
quality of life, the drugs are more tolerable (produce fewer side effects than
other antidepressants) so patients are more likely to continue taking them. They
can also be prescribed with confidence by primary care physicians and
cardiologists. An SSRI also helps counteract the key biologic problems
associated with depression and heart disease. For instance, they help decrease
platelet aggregation, one of the phases of blood clotting, and help normalize
heart rate variability.
"It’s well established that SSRIs are safe medications for cardiac
patients," says Dr. Pozuelo. "That’s reassuring to the public, as
well as to primary care physicians and cardiologists." Physicians who do
prescribe SSRIs for depression in patients with heart disease, however, need to
ensure that the drugs are compatible with the patient’s existing cardiac
medications, says Dr. Pozuelo.
All of the research into the relationship between depression and heart
disease is particularly important because depression is a common disorder. For
instance, depression affects 6 percent of men and 18 percent of women in the
general population and it can occur in approximately 40 percent of the medically
ill.
Education and awareness
Dr. Franco says physicians are focusing on enhancing education efforts to
assist doctors, patients and their families in identifying symptoms of
depression in an effort to treat and monitor patients more consistently. Typical
symptoms of depression include general lethargy for extended periods of time,
excessive guilt, reduced appetite, poor concentration, reduced mobility,
persistent morbid thoughts and the inability to derive pleasure from activities
that were previously enjoyable. Other symptoms include poor sleep, loss of
interest in normal activities, low energy, tearfulness or feeling helpless or
hopeless.
Dr. Franco also stresses the importance of helping the public overcome the
stigma associated with depression. Many people still believe that the disease
stems from character weakness, which simply is not true, she says.
"Depression is a chemical disorder in the brain. As is the case with any
other organ system illness, if the condition is ignored, serious consequences
follow."
After a cardiac event, says Dr. Franco, "patients with depression are at
three to five times greater risk of having another heart attack, arrhythmia or
both. So the depression needs to be promptly identified and treated
effectively."
She also believes that the public needs to be educated about the link between
depression and other medical conditions. It can increase the risk of development
of new disease and impede healing after treatment, as is the case with heart
disease.
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